In a typical carbureted automobile engine, for example, fuel is delivered by a fuel pump from a fuel tank to the carburetor. The carburetor atomizes the fuel in the presence of air to create a combustible mixture of air and fuel which is delivered to the cylinders of the engine. The performance of the carburetor in creating a mixture which will burn cleanly and efficiently in the engine is sensitive to any fluctuations in the pressure of the fuel supplied to the carburetor. Therefore, it is important to accurately regulate the fuel pressure to ensure a uniform delivery of fuel to the carburetor. This is true for fuel injection systems as well.
It is known in the art to regulate the pressure of fuel being pumped from the fuel tank to the carburetor with regulators of the diaphragm-and-spring type. Such regulators typically have an upper chamber exposed to atmosphere, a middle chamber that has a fuel outlet opening that communicates with the carburetor, and a lower chamber that has a fuel inlet opening in communication with the fuel tank. A resilient, flexible diaphragm separates the upper chamber from the middle chamber and a valve separates the middle chamber from the lower chamber, the valve being actuated between open and closed positions by a valve actuating stem extending between the valve and the diaphragm which imparts the movements of the diaphragm to the valve. A diaphragm spring in the upper chamber bearing against the diaphragm urges the diaphragm and valve in one direction and fuel pressure in the middle chamber urges the diaphragm and valve in the other direction. Through selection of a diaphragm spring of the appropriate rate, the fluid pressure in the middle chamber can be maintained at a desired level. Typically, an adjustment screw is provided for changing the amount of force exerted by the diaphragm spring on the resilient diaphragm.
One of the problems with such spring-and-diaphragm regulators is that it can be difficult to convert the movement of the resilient diaphragm into a proper translational movement of the valve actuating stem necessary for obtaining the desired fuel pressure. It is known in the art to mount the valve actuating stem rigidly to the diaphragm by mounting metal plates on either side of the diaphragm, providing the plates and the diaphragm with coaligned holes therethrough and extending a portion of the actuating stem through the coaligned holes and securing it on the other side of the diaphragm as with a threaded nut. This arrangement rigidly secures the actuating stem to the diaphragm to ensure that movement of the diaphragm is reflected in movement of the valve. However, not all types of motions of the diaphragm should effect a movement of the valve actuating stem. For example, the resilient diaphragm may move in a sideways manner or may flex, and these types of movements should not be imparted to the valve actuating stem. Furthermore, this means of attaching the actuating stem to the diaphragm creates a hole in the diaphragm which may be prone to leaking fuel from the middle chamber to the upper chamber, which presents a safety hazard.
Such diaphragm-and-spring type regulators typically have a frusto-conically shaped valve for sealing against a valve seat. With this arrangement the portion of the valve that contacts the seat remains constant; in other words the same "contact patch" bears the burden of sealing the valve over the entire life of the valve, which can decrease the service life of the components of the regulator as a result of wear. Of course, any decreased service life requires a ready access to the various worn components for servicing thereof.
In automobile racing applications, the above identified problems can be magnified many times by the heightened demands placed on the fuel supply system during competition.
Accordingly, it is seen that a need yet exists for a fuel pressure regulator for automobiles which is durable, easily serviced and which converts movements of a pressure responsive diaphragm into translational movements of the valve actuating stem and valve without the necessity of a rigid connection between the valve actuating stem and the diaphragm. It is to the provision of such a fuel pressure regulator that the present invention is primarily directed.